Drive mechanism for fuel burners



DRIVE MECHANISM FOR FUEL BURNERS Filed NOV. 11, 1953 2 Sheets-Sheet l i:ii:

Haw/9y d K Aug. 18, 1936.

r H. J. KEELEY f DRIVE MECHANISM FOR 'FUEL BURNERS 2 Sheets-Sheet 2Filed Nov. 11, 1933 HEA/Ry d AEELE y dbbozmq Patented Aug. 18, 1936UNITED STATES PATENT OFFICE 6 Claims.

This invention relates to a mechanism for driving the grates, feedconveyors, ash conveyors, blowers, etc., of a stoker or burner. It ismore particularly applicable for driving a burner of the typeillustrated in applicants copending application, Serial No. 691,649, butis, of course, not limited to this particular application.

The principal object of the invention is to provide a mechanism whichcan be controlled to advance traveling grate bars, feed conveyors, etc.,at a speed proportionate to the rate of combustion of the fuel.

Another object of the invention is to so construct the device that theincoming power may be alternately employed to drive two or moreindependent drive mechanisms so that a single prime mover may be usedfor all drives, yet need only be large enough to drive any one of thedrives.

A further object is to provide a novel and efficient means foraccurately controlling the air supply to a burner blower.

Other objects and advantages reside in the detail construction of theinvention, which is designed for simplicity, economy, and efficiency.These will become more apparent from the following description.

In the following detailed description of the invention reference is hadto the accompanying drawings which form a part hereof. Like .numeralsrefer to like parts in all views of the drawings and throughout thedescription.

In the drawings:

Fig. 1 is a plan view of the invention applied to a fuel burner of thetype illustrated in the said copending application.

Fig. 2 is a cross section therethrough taken on the line 22, Fig. 1.

Fig. 3 is a enlarged side elevation thereof looking in the direction ofthe arrow 3, Fig. 1.

Fig. 4 is a detail view of the actuating cam.

Fig. 5 is a detail view ofthe ratchet lever.

Fig. 6 is a detail view illustrating the intake of the blower.

In the drawings a portion of a coal feed conveyor such as illustrated inapplicant's said copending application is illustrated at H] and a gratedrive shaft, for driving a traveling grate of the type illustrated insaid copending application, is shown at I I. A fan l2 mounted in a fanhousing l3 supplies the combustion air to the burner.

The present invention resides in means for driving the conveyor Hi, thegrate drive shaft I l, the fan l2, and for controlling the air intake ofthe fan housing 13.

The invention comprises an actuating cam [4 mounted on a cam shaft 15actuated from a speed reducer IS. The power is furnished to the speedreducer 16, from a drive motor 11. At each side of the cam M, a ratchetshaft I8 is positioned. The ratchet shafts l8 carry cam follower levers5 59 secured thereto and provided with suitable rollers it for rollingon the periphery of the cam Id. The rollers are maintained in constantcontact with the cam by means of suitable springs 25. Thus as the camrotates, it will impart an 10 alternating rotation to the ratchet shaftsl8.

Each of the ratchet shafts I8 is provided with a pawl arm 22, on theextremity of each of which,

a pawl 23 is hinged. One of the pawls 23 actuates a ratchet gear 24which drives the feed con- 15 veyor H3 through the medium of bevel gears25. The other pawl 23 actuates a ratchet gear 26 mounted on the gratedrive shaft ll. Each pawl is provided with a pawl spring 21 whichconstantly urges it towards its gear.

It can be readily seen that as the pawls 23 swing toward the gears theywill contact the teeth of and rotate the latter and as they swingrearward they will ride over the gear teeth. The pawls are so arrangedthat they can be caused to engage more or less of the gear teeth so asto rotate the gears any desired interval. This is accomplished by meansof a stop lever 28 which is hinged on the pivot of the pawl 23 andcontacts with the latter. If the stop member 28 is swung outwardly itwill limit the amount of descent of the pawl so as to maintain it at aheight which will not allow it to contact with the gear teeth until itapproaches the extremity of its movement. If the stop is swungdownwardly it lowers the pawl 23 so that it will contact with the gearteeth earlier in its arc of movement.

The inward and outward movement of, the stop lever 28 is accomplished bymeans of a wedge 30 which is supported from a collar 3| splined on theratchet shaft l8 so that it may be moved longitudinally thereof but mustrotate therewith. It can be seen that as .the wedge 30 is movedtoward'the pawl lever 22 it will enter between the pawl lever and thestop lever so as to raise the latter. If moved away from the pawl lever22 it will allow the stop lever to be drawn toward the pawl lever bymeans of a tension spring 32.

The longitudinal movement of the wedge 30 may be accomplished by meansof a manually actuated screw 33 which is threaded through a yoke 34engaging the collar 3|, as shown on the drive of the grate shaft II. Itmay also be operated by means of a motor, as shown on the 7 through asuitable speed reducer 38.

the motor 3'! moves in one direction it will I withdraw the wedge frombetween the levers owing to the springs 2|. jquired need onlybesufiicient to drive either the conveyor H). or the shaft l'l sinceonly 'one of' thesermembers is being driven ata "time.

conveyor drive. In the latter construction, a yoke is threaded on athreaded shaft 36. The shaft 35 is driven by means of a motor 31 Thus as22 and 28 and as it moves in the other direction it will force the wedgebetween these levers'so as to constantly control the number" of teeth tobe engaged by the pawl 23.

The fan #2 is preferably mounted on an extension motor shaft 39 from thedrive motor IT. The air from the fan discharges through a conduit 40 tothe combustion chamber. The air to the fan intakes through the sides ofthe housing 13. The intake opening'is surrounded by a series ofirisplates 4|, each of which is pivoted adjacent its one extremity on both astationary ring 42 and a rotatable ring 43. V43 is rotated, it willswing the iris plates inwardly over the intake opening so as to reducethe size thereof, as indicated inbroken line in Figflfi; The rotation ofthe ring 43 may be accomplished through the medium of an arouat'e rack'44 and a rack pinion 45. pinion 45 is driven from a small motor 46'througha suitable speed reducer 41.

It is preferredto have the motors 31 and 46 and the various electricalcontrols operate from direct current in order that a variable speed maybe effectively obtained. Since practically all installations will bemade where only alternating current is available, a direct currentgenerator 48 is provided. The alternating current "is used to drive themotor H at a constant speed.

The motor ll then drives thegenerator 48 to furnish the current for themotors 31 and 46.

'It isdesired to call attention to the fact that while the cam' I4 isactuating one of the follower levers lj9, the other follower lever I9 isdescending so that it not only absorbs no power but actually assists'therotation of 'the cam 14,

Thus, the power re- A stop claw '49 is preferablyformed on each pawl 23so as to engage'in the teeth of the ratchetgear at the extremity of thepawl stroke so as to definitely stop the gear at this. point 7 andprevent it from coasting.

"The cam I4 is preferably, but not necessarily, constructed asillustrated in Fig; 4' so that a variation may beobtained in itseffective length.

This is'accomplished by mounting the cam on a shaft frame 50 having ashape which allows movement on the shaft I8. Adjusting bolts 5| passthrough the frame 50, there preferably being one bolt on each 'side ofthe 'cam I4. These bolts are threaded through the shaft f8 '50 thatrotation of the bolts varies the position of the frame 59 on'the shaftand varies the axial "point or the effective length of the cam 14.

It can be seen from theabove that an exceed- "ingly accurate and minuteadjustment of the movement of the conveyor 10 and the grate bars.

g the opposite direction.

It is possible that the motor 31 might start to "operate at atime whenthe pawl 23 was in en- Thus, as i the ring I The rack gagement with theteeth of the ratchet gear. At this time it would be practicallyimpossible for the wedge to enter between the levers 22 and 28 whichmight result in damage to the motor. To avoid this a friction clutch 52is positioned between the speed reducer 38 and the shaft 36 which allowsthe motor 31 to idle until'the load is released from the pawl 23. a

It is desired to call attention to the fact that Without departing fromthe spirit of the invention.

Having thus describedthe invention, what' i's claimed and desiredsecured by Letters Patent is: V

1. Means for actuating a grate drive shaft comprising: a cam; means fordrivingsaidcam; a pawl shaft positioned atone side of said earn;

a cam follower projectingf'from said pawl shaft into a contact with saidcam; a pawl arm projecting from said pawl shaft; a pawl-lunged to saidpawl arm and extending therefrom; a ratchet gear in contact with saidpawl, and operatively connected with said grate drive shaft; a stopmember movably supported by said pawl arm so as to contact with saidpawl and limit its are of contact with said ratchet gear; a wedgemember; a collar slidably mounted on said pawl shaft and supportingsai-dwedge member; and means for moving said collar longitudinally of saidpawl shaft so as to project said wedgemember into contact with said stopmember to vary the position of the latter. 5

2. Means for actuating the grate drive shaft ofa fuel burner comprising:a cam; means for driving said cam; a pawl shaft positioned at one sideof said cam; a cam follower projecting from said pawl shaft into acontact with-said cam; a pawl arm projecting from said pawl shaft; apawl hinged to said pawl arm and extending therefrom; a ratchet gear incontact:

with said pawl and operatively connected with said grate drive shaft; astop member 'movably supported by said pawl-arm so .as to contact 'with:said pawl and limit its arc of contact with said ratchet gear; a' wedgemember; a collar; slidably mounted on said pawl shaft and supportingsaid wedge memberpa threaded -sha'ft a yoke actuated by saidthreadedshaft and 00m nected with said collar so asf' that rotation ol saidthreaded shaft will move said collar Rough r69,

tudinally of said pawl shaft so as to project said wedge member intocontact with said stop member to vary the position of the latter.

3. .Means for intermittently rotating -a drive --shaft comprising: aratchet wheel :on-sa'id shaft;

a pawl shaft positioned alongsideaand parallel ito said' drive shaft;means for 'rockingsaid pawl shaft through'a preset arcya pawl armprojecting from said pawlishaft; a pawl hinged to said pawl arm andextending over said ratch et wheel; a pawl supporting member hinged tosaid arm -and contacting said pawl; a wedge tremity positioned betweensaid arm and said #5 pawl supporting member; and means for varying theposition of said wedge member along said pawl shaft so as to project orwithdraw said wedge-shaped extremity and cause said pawl supportingmember to vary the effect of said pawl on said ratchet wheel.

4. Means for intermittently rotating a drive shaft comprising: a ratchetwheel on said shaft; a pawl shaft positioned alongside and parallel tosaid drive shaft; means for rocking said pawl shaft through a presetare; a pawl arm projecting from said pawl shaft; a pawl hinged to saidpawl arm and extending over said ratchet wheel; a pawl supporting memberhinged to said arm and contacting said pawl; a wedge member slidablymounted on said pawl shaft, said latter member having a wedge-shapedextremity positioned between said arm and said pawl supporting member; athreaded shaft extending alongside and parallel to said pawl shaft; anut carried on said threaded shaft;- a yoke projecting from saidthreaded shaft to a contact with said wedge member; and a motor forrotating said threaded shaft so as to move said wedge-shaped extremityinto more or less contact with said pawl supporting member so as to varythe effective are of movement of said pawl.

5. Means for actuating the fuel feed mechanism of a fuel burnercomprising: a pawl shaft; a cam shaft parallel to said pawl shaft; a cammounted on said cam shaft; a follower arm extending from said pawl shaftover said cam and resting thereon; a pawl arm extending upwardly fromsaid pawl shaft; a ratchet shaft positioned parallel to said pawl shaft;a ratchet wheel mounted on said ratchet shaft; a pawl extendingoutwardly from the upper extremity of said pawl arm over and intocontact with said ratchet wheel; means for rotating said cam shaft so asto oppositely rock said pawl shaft; a movable stop member contactingsaid pawl; a wedge member mounted for slidable movement along said pawlshaft and acting through said stop member to limit the arc of contact ofsaid pawl with said ratchet wheel; and means for moving said wedgemember longitudinally of said pawl shaft.

6. Means for actuating the fuel feed mechanism of a fuel burnercomprising: a pawl shaft; a cam shaft parallel to said pawl shaft; a cammounted on said cam shaft; a follower arm extending from said pawl shaftover said cam and resting thereon; a pawl arm extending upwardly fromsaid pawl shaft; a ratchet shaft positioned parallel to said pawl shaft;a ratchet wheel mounted on said ratchet shaft; a pawl extendingoutwardly from the upper extremity of said pawl arm over and intocontact with said ratchet wheel; means for rotating said cam shaft so asto oppositely rock said pawl shaft; a movable stop member contactingsaid pawl; a wedge member mounted for slidable movement along said pawlshaft and acting through said stop member to limit the arc of contact ofsaid pawl with said ratchet wheel; and means for moving said wedgemember longitudinally of said pawl shaft; a yoke member engaging saidwedge member; a threaded shaft for moving said yoke member so as to movesaid wedge member longitudinally of said pawl shaft; and

a reversible, variable speed motor for operating u said threaded shaft.

HENRY J. KEELEY.

